1. Technical Field
This invention relates to fiber optic cable payout systems for command guided missiles and, more particularly, to a flight launched fiber optic dual payout system.
2. Discussion
In certain command guided missile systems, a long, small diameter, fiber optic cable is utilized to maintain a data link between the missile and its point of launch, or launch platform, throughout the flight of the missile. The fiber optic data link (FODL) facilitates jam-free command communications between the missile and the launch platform's fire control system and allows the guidance of the missile to be remotely controlled by commands originating from the launch platform.
However, fiber optic data links require that the fiber optic cable, itself, be stationary relative to the air through which the missile is traveling, as opposed to being dragged through the air behind the missile. This is due to the fact that at missile velocities, if the cable were dragged behind the missile, the aerodynamic force exerted on the cable (i.e. drag force) would, after a short distance such as a few hundred feet, for example, be sufficient to break the cable and interrupt the fiber optic data link. For this reason, the fiber optic cable is dispensed or "paid out" in the air behind the missile by a missile dispenser which is part of a "fiber optic payout system."
If the launch platform is also moving relative to the air when the missile is launched, as in missiles launched from aircraft, the launch platform must also have a dispenser to pay out the fiber optic cable, in addition to the missile dispenser. The combination of the two dispensers, together with any corresponding mechanical, electrical and optical components, constitute a "fiber optic dual payout system."
To date, experimental flight launched fiber optic dual payout systems employ the ordnance (i.e. the missile) and a data-link pod on two separate launch stations of the launch platform (i.e. wing stations on the aircraft), each having a dispenser for paying out the fiber optic cable. The fiber optic cables in the separate dispensers on the ordnance and the pod are connected by a reinforced cable splice, or "ruggedized" leader line, which is installed at the time the ordnance is mounted on the aircraft. However, these experimental systems have presented several design difficulties, such as how to store and protect the leader line during the flight of the launch platform, which may reach mach velocities, as well as how to release the leader line from storage just prior to missile launch. Further, these systems require the additional installation step of connecting the leader line between the ordnance and the data-link pod at the time that the ordnance is mounted on the aircraft. Still further, these systems have inherently limited the ordnance payload which may be carried on the launch platform because two launch stations on the launch platform are required for each single ordnance.